I think it's possible as far as I remember. I was pretty close to it when I had my op prayer build. Now that the oh heals are fixed maybe it will work better. Although my disco ball build was the fun one, but was bugged at the time. With that defence build, adding maxed out prayer would be semi immortal. Or at least very annoying to kill. My longest before forfeit was 17 rounds in top 2% . Although I only used it when I wasn't actively playing. Based off Griffons "punch me till you die"build.